Safety deposit box lock



April 7, 1964 R. T. ELLIS ETAL 3,127,759

' SAFETY DEPOSIT BOX LOCK Filed Fb. 27, 1961 s Sheets-Sheet 1 2o 3 |||--O 35 1 so 36 42 Z 2 29 32a 37 3| T t 34a.

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INVENTORS ROY T- ELLIS 8. STEPHEN A- DENMAN ATTORNEYS ApriI 7, 1964 Filed Feb. 27, 1961 FIG. 4

R. T. ELLIS ETAL 3,127,759

SAFETY DEPOSIT BOX LOCK 3 Sheets-Sheet 2 !NVENTORS ROY T. ELLIS & STEPHEN A. DENMAN ATTORNEYS April 7, 1964 R. T. ELLIS ETAL SAFETY DEPOSIT BOX LOCK 3 SheetsSheet 3 Filed Feb. 27, 1961 FIG.

FIG.

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FIG. II

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INVENTORS ROY T. ELLIS 8 STEPHEN A. DENMAN ATTORNEYS 49 I07 34h 30h United States Patent Ofilice 3,127,759 Patented Apr. 7, 1964 3,127,759 SAFETY DEPOSIT B'OX LUCK Roy I. Eilis, 2-43 W. Apple St., Dayton 2, Ghio, and Stephen A. lDennian, Piqua, (Ihio; said Denman assignor to said Eiiis Filed Feb. 27, I961, Ser. No. 91,915 22 Claims. (Cl. 7il-339) This invention relates to a lock and especially to that type of lock that is ordinarily used with safety deposit boxes and the like. It has other uses.

This lock includes a housing having a retractable bolt therein that is controlled by the positions of a plurality of floating primary tumblers. The lock has a guard key nose and a customer key nose located toward the opposite ends of the primary tumblers, and the proper sequence of the proper keys must be operated in both key noses before the tumblers can be properly positioned to release the bolt.

To be unlocked the lock requires operation of one or more keys in the guard key nose. The guard key ends of the primary tumblers include a plurality of slots within which one end of a lever is movable only when such ends of the tumblers are positioned so that the slots are aligned. Until the lever so moves into the slots, it blocks retraction of the bolt. Thus, an object of the invention is to provide obstruction to the bolt when the guard key ends of certain tumblers are not aligned by a key or keys.

Another feature of the lock is its inclusion of a plurality of secondary tumblers equal in number to the primary tumblers, the secondary tumblers completely surrounding the customer key nose. Hence, the secondary tumblers prevent the detection of the positions of certain parts of the primary tumblers by the introduction of probes and the like into the customer key nose.

A further object of the invention is to provide a lock having floating tumblers associated with two key noses and positive blockers adjacent each key nose opposing opening of the bolt, which lock requires the positioning of each end of the floating tumblers by its key in its key nose to release the blocker at such end, both blockers being required to be released as a prerequisite to opening of the lock.

A further object is to provide a lock of the foregoing type that requires a key to be left in place in each of the two key noses as a prerequisite to opening of the bolt. An additional object is to provide a lock of the foregoing type that can be reclosed regardless of which key is actuated and withdrawn first. Another object is to provide a lock of the foregoing type that may require as many as three keys for its operation.

A principal object of the invention is to provide a lock having special means for preventing picking of the lock. Specifically, an object is to include such anti-picking means that are controllable by the guard end of the lock so that operation of the guard key end by the proper key or keys is a prerequisite to establishing the position of the tumblers for operation by the customer key.

Another object is to provide a lock that has means for preventing detection of the positions of parts of the lock that must be set prior to the retraction of he bolt, which detection is easy in conventional locks by the use of probes and the like introduced into the customer key nose.

Yet another object of the invention is to provide a lock that is operable by keys inserted through two separate key noses with a plurality of tumblers that must be properly positioned by keys in these key noses, wherein the positioning of either end of the tumblers is controlled by keys in both key noses.

A further, and important, object of the invention is to prevent reading of the guard key by probes inserted in the guard key nose when the locking bolt is retracted and there is no key in the guard key nose.

Still another object of the invention is to provide a lock that has a plurality of tumblers with slots in them that must be aligned before the bolt can be retracted, with means for preventing detection of the position of the slots by sound detection means. The details of this object are more particularly set forth in the co-pending application of Roy T. Ellis and Stephen A. Denman, Serial No. 46,447, filed August 1, 1960.

Further objects and advantages will be apparent from a more detailed description of the invention.

In the drawings:

FIGURE 1 is a side elevation view of the lock with the cover removed;

FIGURE 2 is a view in section taken along the line 2-2 of FIGURE 1, but with the cover in place;

FIGURE 3 is a side elevation view of the relationship between a typical primary tumbler and a typical secondary tumbler and between these tumblers and the key noses;

FIGURE 4 is a view in section taken along the line 44 of FIGURE 2, but with the primary and secondary tumblers removed;

FIGURE 5 is a view in section taken along the line 5-5 of FIGURE 4;

FIGURE 6 is a view in section taken along the line 66 of FIGURE 4;

FIGURE 7 is a view in section taken along the line 77 of FIGURE 4;

FIGURE 8 is a view in section taken along the line 88 of FIGURE 4;

FIGURE 9 is a back view of the front cover shown removed from the lock housing;

FIGURE 10 is a view in section taken along the line 1il1il of FIGURE 2;

FIGURE 11 is a side elevation view of the customer key nose;

FIGURE 12 is a back view of the customer key nose;

FIGURE 13 is a side elevation view of the guard key nose;

FIGURE 14 is a back view of the guard key nose;

FIGURE 15 is a view in section taken along the line 1515 of FIGURE 3; and

FIGURE 16 is a side elevation view of the detent lever.

In general, the lock includes a housing 20 having a removable cover 21. The cover 21 has a pair of sleeve openings'22 and 23 for receiving a pair of key noses 24 and 25. The key nose 24 has a slot 24a for receiving a key. The key nose 25 has a similar slot 25a for receiving one or more keys. The left hand nose 24 is for a customer key and the right hand nose is for a guard key (plus another key or keys, as will be explained). A locking bolt 2-6 is slidably mounted against tracks on the back wall of the housing 29, and is controlled by the proper sequence of correct keys in the key noses 24 and 25. The locking bolt 26 has a projecting end27 that moves through an opening 28 in the left side wall of the housing 20.

The locking bolt 26 has a tr apezoidailly shaped primary bolt lug 29 on its front face extending forwardly to adjacent the inner surface of the removable cover 21. A plurality of primary tumblers 39a through 34th are supported forwardly of the bolt 26, and normally the edges of at least some of a plurality of primary tumblers 3611 through 3% block the lug 29 to prevent retraction of the locking bolt.

The tumblers Sila through 30h are floating tumblers, e.g., have no fixed pivots. There is a fixed primary tumbler pin 31, but each of the primary tumblers has an elongated slot 32 through which the pin 31 extends to guide the primary tumblers only.

While the primary tumblers normally block the primary bolt lug 29, each of these tumblers has a trapezoidally shaped slot 33 that will receive the lug 26 when all the slots 33 are aligned and opposite the lug 29. This positioning of the tumblers is accomplished upon turning the proper keys in the key noses 24 and 25. The several slots 33 have different positions with respect to one another, and the teeth of the proper key for each lock are arranged with reference to these different slot heights.

[It should here be noted that the primary tumblers Stla through 30h normally rest upon the top of the key nose 25, but are spaced from the key nose 24 by, and rest upon, a plurality of secondary tumblers 34a through 34h. In fact, the primary tumblers 30a through 3011 are biased against the nose 25 and the secondary tumblers 34a through 34h by a plurality of bent wire springs 35, the ends of which bear against the top wall of the housing and the centers of which are received within slots 36 in the tops of the tumblers. (See FIGURES 3, and

The secondary tumblers 34a through 34h are pivotal about a secondary tumbler pin 37 and completely surround the key nose 24. The holes 38 in the secondary tumblers through which the customer key nose 24 projects are irregularly shaped, with an extension 39 to allow free insertion of a key. There is also a key tooth bearing surface 40, and an extension 41 to prevent blocking of the secondary tumbler by the key nose 24.

While all of these parts will be described in further detail, it is now apparent that the primary tumblers 39;: through 30h are movable from their normal blocking positions by the action of keys in both key noses 24 and 25.

The proper key (or keys) within the guard key nose directly engages at least some of the guard key bearing surfaces 42 on the primary tumblers a through 30h and raises the right hand ends of the primary tumblers. The proper key within the customer key nose 24 raises at least some of the secondary tumblers 34a through 34h which, in turn, raise the corresponding primary tumblers to align and position the slots 33 for receiving the primary bolt lug 29.

There is a secondary bolt lug 45 mounted on the lower arm of the bolt 26, to be pivotal about a pivot pin 46 that is fixed to the locking bolt 26. The secondary bolt lug 45 is normally positioned by a torsion spring 48 against a stop 47 projecting forwardly on a ledge on the bottom edge of the bolt 26. The lug 45 has a backward-1y bent end 45a for a purpose to appear.

Without the proper key action in the guard key nose 25, the secondary bolt lug 45 is blocked by the blocking end 49 of a bolt release lever 50, as shown in FIGURE 1. However, the bolt release lever has a hub 51 that is pivotally mounted on a pin 52 attached to the housing, and is biased to rotate in a counterclockwise direction by a torsion spring 53. The bolt release lever has a laterally projecting pin 54 at its upper end, and the pin 54 norm-ally engages the right hand edges of at least some of the primary tumblers 30a through 30h and prevents rotation of the bolt release lever 50 away from the position illustrated in FIGURE 1.

Each of the primary tumblers 30a through 30h has a trapezoid-ally shaped guard end slot 55, and when the slot-s 55 are aligned and properly positioned by the action of a key or keys within the guard key nose 25, the pin 54 can slip into the slots 55, allowing the bolt release lever 50 to pivot to the position illustrated in FIGURE 4. In this position of the bolt release lever 50, the secondary bolt lug 45 releases the locking bolt 26 because the lug 45 can slide over the blocking end 49 of the bolt release lever 50, as is apparent in FIGURE 4.

The lock may be designed so that more than one key must be operated in the guard key nose before the slots 55 are aligned. For this operation, the right hand edges of the primary tumblers 30a through 3911 may be extended to a number of different lengths according to the number of different keys required to operate the guard key end of the lock. The lock illustrated requires two suck keys (one of which may be the customer key), and the dotted line of FIGURE 3 shows that the right hand edge 60a of one or more of the tumblers 30a through 30h is further to the left than the edge or edges 60. Consequently, when one key (for example, the customer key) is turned within the guard key nose 25, the teeth of that key bear against the guard key bearing surfaces 42 of these primary tumblers having the extended edges 60. The proper first key will align the slots 55 of these primary tumblers, and the pin 54 can fall part of the way into these slots 55. However, because the positions of the slots 55 of the remaining primary tumblers are not affected by the first key operated within the nose 25, the bolt release lever 50 is blocked from complete counterclockwise rotation by the abutment of the pin 54 against the edges 60a of the remaining primary tumblers. In this condition, the blocking end 19 of the bolt release lever 50 still blocks the secondary bolt lug 45.

When the second (guard) key is operated within the nose 25, its teeth operate against the guard key bearing surfaces 42 of the remaining primary tumblers 30a through 3011 that still obstruct the pin 54. The guard key aligns the slots 55 of these remaining primary tumblers, and the pin 54 can then move all the way into all the slots 54. When the proper sequence of the proper keys is used, the secondary bolt lug 45 is unblocked.

Whether or not the guard key end of the lock is operable by a single key or by a plurality of keys, the primary tumblers 30a through 30h are released from the pin 54 of the bolt release lever 50 only upon counterclockwise return rotation of the last such key. Such action is accomplished by a reset cam 61 rotatably mounted near the rearward end 62 of the guard key nose 25, which end is of reduced diameter (see FIGURE 11). The reset cam '61 is positioned between the back wall of the housing and a shoulder 63 on the guard key nose 25 that terminates the reduced end 62. The end 62 of the key nose 25 is journalled within a lug 64 on the back wall of the housing.

The reset cam 61 has a slot '65 in it :for receiving the end of a long key. Shorter keys, like the customer key and any keys inserted into the guard key nose 25 before the last key, will not reach the slot 65. The last key (usually the guard key) is a longer key and is the only key that will operate the reset cam 61.

There is a trip dog 66 mounted for rotation about the hub 51 and biased by a trip dog return spring 67 against a trip dog stop 68 that depends from the bolt release lever 50.

The reset cam 61 has an actuating surface 69 for engaging a retracting surface 70 on the trip dog 66. There is a reset surface 71 on the reset cam 61 for engaging a return surface 72 on the trip dog. Thus, while the last, and longest, key inserted within the guard key nose 25, when rotated clockwise, establishes the aligned position of any theretofore unaligned primary tumbler slots 55 (allowing the bolt release lever to rotate to the position shown in FIGURE 4), it also rotates the reset cam 61 in a clockwise direction. This rotation of the reset cam causes it, through engagement between the actuating surface 69 and the retracting surface 70, to rotate the trip dog 66 in a counterlockwise direction against the force of the trip dog return spring 67 and away from the trip dog stop 68. The lengths of the reset cam 61 and the trip dog 66 between these operating surfaces is such that the reset cam releases the trip dog prior to the complete clockwise rotation by the last key, and the trip dog snaps back against the trip dog stop 68 under the action of the trip dog return spring 67. Thereafter, when the last key in the guard key is turned clockwise, the reset surface 71 of the reset cam engages the return surface 72 on the trip dog and forces the trip dog to rotate in a clockwise direction. As the trip dog rotates, it operates through the trip dog stop 63 to rotate the bolt release lever in a clockwise direction. During this action, the engagement between the reset surface 71 and the return surface 72 is maintained long enough to revolve the pin 54 beyond the right side of the openings of all the slots 55. At this point, the primary tumblers 3% through 3% fall downward against the nose 25 under the force of the tumbler return springs 35. The final counterclockwise rotation of the reset cam causes it to slip past the return surface 72 on the trip dog 66. Then the bolt release lever Eitl can return under the force of the spring 53 to its normal position, as illustrated in FlGURE 1.

In order to properly position the reset cam 61, there is a detent lever 75, shown particularly in FIGURE 16, pivotally mounted about a pin 76 supported at the right side wall of the housing. The detent lever 75 has a right angle notch 78 that engages a corner 79 of the reset cam 61. The detent lever '75 is biased against the reset cam 61 by a spring 80 to assure alignment of the slot 65 with the key slot 25a in the guard key nose 25. The detent lever 75 is forced out of engagement with the corner 79 when the reset cam 61 is rotated.

Upon operation of the lock with the proper sequence of the proper keys with resultant alignment of all the slots 33, alignment of all the slots 55, and unblocking of the secondary bolt lug 45, the locking bolt 26 can be re tracted. Referring to FIGURE 4, there is a bolt operating cam 84 with a tongue 85 that fits within a slot 86 in the customer key nose 24. Thus, the bolt operating cam $1 rotates with the customer key nose 24. The bolt operating cam has a bolt retracting surface 87 for engaging the edge 88 of an extension 89 on the locking bolt 26. The initial contact between the bolt retracting surface 87 and the projection surface 88 occurs only after about a ninety degree clockwise rotation of the cam 84. The bolt operating cam 64 also has a bolt actuating surface 99 that engages a return surface 91 on the locking bolt when the customer key nose 2d is rotated in a counterclockwise direction. The surfaces 941 and 91 make contact only after about a ninety degree counterclockwise rotation of the cam 34.

The total are of rotation of the key nose 24 in either direction is about 135. However, the locking bolt is either retracted or extended only during about the last 45 of rotation of the key nose 24 and the bolt operating cam 84. This lost motion in the rotation of the bolt operating cam is intentional, and the trapezoidal shapes of the slots 33 on the primary tumblers 3% through Stilt, as well as the trapezoidal shape of the primary bolt lug 29, are important in association with this lost motion. Because of the size of the slots 33 relative to the primary bolt lug, the tumblers can rock about the tops of the secondary tumblers 34:; through 34h. And the extent of rocking that is possible is such that after all keys have been removed from the guard key nose 25, and the primary tumblers have dropped against the guard key nose, the reextension of the locking bolt 26 upon counterclockwise rotation of the customer key does not raise the primary tumblers from the guard key nose 25. In addition, the angular lost motion of the bolt operating cam 84- allows the tumblers to be lowered by the customer key prior to movement of the wider part of the lug toward the narrower part of the slots 33.

The fact that the primary tumblers remain at rest upon the guard key nose 25 prevents the reading of the guard key by the insertion of probes into the guard key nose. If the tumblers were lifted from the guard key nose upon counterlockwise rotation of the customer key, their relative positions could be determined by a probe in the guard key nose, and, then, by projecting the relative distances of the guard key nose and the customer key nose from the slots 33, the exact configuration of the guard key could be calculated.

The locking bolt 26 is limited to horizontal movement by a guide comprising a tongue 92 on the bolt that slides within a groove 93 in the rear wall of the housing. On the front face of the locking bolt 26 there is a tumbler guide rib 94.

Finally, referring to FIGURES 2, 9 and 11 through 14, there are means for controlling the extent of rotation of the key noses 24 and 25. The noses 24 and 25 are provided with enlarged heads 95 and 96, respectively. Spaced from the tops of the heads 95' and $6 are a pair of annular shoulders 97 and 93, respectively, that extend somewhat more than half the distance around the circumference of the heads 95 and 96. The terminations of the shoulder 97 define a pair of steps 99 and tea. The terminations of the shoulder 93 define a pair of stops 191 and 102.

The stops 99 and we of the customer key nose cooperate with a corresponding stop projection Hi3 cast in the inner part of the sleeve 22 to define the limits of rotation of the key nose 24. Likewise, the stops Th1 and 162 cooperate with a pair of stop projections lit-4 and Th5 cast in the inner part of the sleeve 23. The arrangement of these stops prevents alignment of the key nose slots Evith any part of the tumblers except the key contact suraces.

There is ready access to the interior of the lock housing upon removal of the cover 21. The cover is fastened to the housing by a bolt 1% threaded into a cover retaining post 1%7.

As set forth in detail in the previously mentioned copending application of Ellis and Denman, assigned to the same inventor as this application, there are a plurality of randomly spaced, randomly shaped, and randomly sized holes 1% in the primary tumblers Flila through 3tlh to prevent detection of the tumbler slots by means of sound detection. The holes doll confuse the resonance characteristics of the tiunblers.

The back wall of the housing 20 has a plurality of screw holes 119, 111, 112 and 113 through it. These holes 11G are conveniently positioned at the corner of the back wall. The cover 21 has corner notches 114 to permit access of a screw driver to the mounting screws.

In the past, with conventional looks, it has been easy to remove a look from an opened vault door and to replace that look with another. If a guard opens one of these conventional looks with his and a customers key, thereafter returning the customer key to the customer while leaving the vault door open, the temporary absence of the customer for about thirty seconds affords the guard sufiicient time to replace the lock with a similar look. If the guard has the customer key to the substituted lock, he can open the door to the safety vault once the customer has left.

The lock of this invention prevents such substitution by a guard or other unauthorized person. The lower left hand end of the bolt 26 (as viewed in FIGURE 4) is extended to provide a corner 11$. The upper left hand end could be similarly extended. When the bolt 26 is extended, the corner 112. occupies a position between the head of a screw in the adjacent hole 111) and the corresponding notch 114 in the cover 21, obstructing the access of a screw dniver to that screw. Since the customer key is always returned to the customer when he leaves his opened vault, and since the counterclockwise rotation of the customer key forces the bolt operating cam $4 to extend the bolt 26, the guard cannot remove the look.

When authorized removal of the lock is necessary, the bolt 26 can be rehracted, reacting with it the corner 115 to provide access to the screw through the hole Operation This lock operates by means of one or more keys turned within the guard key nose 25 and a single key turned within the customer key nose 24. Assuming that the lock is in the condition illustrated in FIGURE 1, with the bolt 26 extended, a key is inserted into the guard kev nose 25 and is rotated. As that key is rotated, its teeth are arranged to bear against the key bearing surfaces 42 of those primary tumblers 30:: through 3% having extended right hand edges 6%. While it will be appreciated that the slots 55 are not initially aligned, the teeth of the key are of irregular shapes so that upon rotation of the key, the right ends of the primary tumblers 30a to 36h that have the edges 60' are raised so as to bring the slots of these first raised primary tumblers into alignment opposite the pin 54. When this is accomplished the pin 54 snaps a short distance into those slots 55 that are thus aligned until it is obstructed by the edges 60a of the not yet aligned primary tumblers. The pin 54 then holds the right ends of the now aligned tumblers elevated, even when the first key is removed.

Since the first key introduced into the key nose 25 is not long enough to reach the slot 65 in the reset cam 61, that first key, when rotated counterclockwise, and removed, will not pivot the bolt release lever 50, and the pin 54 will remain part of the Way within the aligned slots 55.

Also at this point in the operation, the movement of the pin 54, part of the way within the slots 55 does not free the blocking end 49 of the blocking lever 56 from ob- SHTLlCllVfi position relative to the secondary bolt lug 45.

When the second or guard key is introduced into the guard key nose 25, it moves within the slot 65 of the reset earn 61 since it is a longer key. \Vhen this second key is turned in a counterclockwise direction, it aligns the slots 55 of the remaining primary tumblers, allowing the pin 54- to be moved all the Way into the slots 55 under the action of the torsion spring 53. It then holds the right ends of all of the tumblers 30a to 3011 in upward position. This full movement of the pin 54 lowers the blocking end 49 of the bolt release lever 50 to a position below and out of alignment with the bolt lug 45, as shown in FIGURE 4.

As the guard key ends of the primary tumblers 30a through 30h are raised by keys operated in the guard key nose 2.5, the slots 33 are lowered because in this action the floating primary tumblers pivot about their rest position-s on top of the secondary tumblers 34a through 3411. If desired, one or more of the slots 33 may initially be above the lug 29, so that when the left ends of the primary tumblers are moved downwardly as aforesaid, these particular slots move into positions opposite the primary bolt lug 29. For these tumblers, the customer key introduced into the customer key nose 24 will have teeth arranged to be ineffective upon the already positioned primary tumblers.

The slots '33 of the remaining primary tumblers are aligned and positioned opposite the primary bolt lug 29 by rotation of the customer key in the customer key nose in which rotation the customer key teeth engage the edges 40 of the secondary tumblers and rock the same about the pivot 37, and the secondary tumblers, in turn, engage the inner edges of the primary tumblers and lift their left ends, while their right ends rock about the arm 54 in the slots 55 or the guard key. Thereafter, continued rotation of the customer key nose causes the bolt retracting surface 87 of the bolt operating cam 84 to engage the projecting surface 88 on the bolt 26 and retract the projecting end 27 of the locking bolt.

A special feature of the secondary tumblers is the fact that they completely surround the customer key nose 24. This construction of the secondary tumblers prevents reading of the slot positions by probes inserted through the customer key nose, and also prevents false displacements of the blocker '50 and the lug 45 by probes inserted in the customer key nose.

To return the lock to locked position, either the customer key in the customer key nose or the guard key in the guard key nose 25 is removed first. Assuming that it is the guard key that is removed first, when the guard key nose 2 is rotated, the reset cam 61, which had moved past the trip dog 66 and allowed the trip dog 66 to return against the stop 68, engages the return surface 72 of the trip dog 66 and presses the trip dog against the stop 68. The consequent movement of the stop 68 causes the bolt release lever 50 to pivot and retract the pin 54 from the slots 55. In this event, the wire springs 35 press the guard key ends of the primary tumblers against the guard key nose 25. ll the guard key is removed first, it displaces the lever 50 clockwise to release the pin 54 from the slots 55. At this point the end 49 of the lever 50 may be beneath the lug 45. But the secondary bolt lug 45 does not interfere with the return of the bolt release lever 50 because the secondary bolt lug can be moved against the force of the spring 48.

As the customer key nose is rotated in a counterclockwise direction, the bolt operating cam 84 engages the return surface 91 of the bolt 26 and re-extends the projecting end 27 of the bolt. At that same time, it releases the primary tumblers from their engagement with the primary bolt lug, and these tumblers fall against the upper edges of the secondary tumblers 34a through 34h.

Various changes and modifications may be made within the process of this invention as will be readily apparent to those skilled in the art. Such changes and modifications are within the scope and teaching of this invention as defined by the claims appended hereto.

What is claimed is:

1. In a lock having a bolt slidable to a retracted position upon operation of the proper sequence of the proper keys, first and second key noses, a plurality of primary tumblers for normally blocking retraction of the bolt, first means on each tumbler requiring mutual alignment prior to retraction of the bolt and additional means on each tumbler requiring mutual alignment as a prerequisite to the retraction of the bolt, the first means being mutually alignable and the additional means being mutually alignable in response to operation of the proper sequence of the proper keys within the key noses.

2. The lock of claim 1 wherein the second mentioned means comprises a plurality of slots with a spring biased pin movable within the slots only when the slots are aligned, and means controlled by the pin for obstructing the retraction of the bolt except when the pin is Within the slots.

3. The lock of claim 2 including means responsive to the removal of a key from one of the key noses for disengaging the pin from the slots.

4. In a lock having a housing with a retractable locking bolt, a plurality of primary tumblers movable from positions normally blocking retraction of the bolt to unblocking positions, a sloted key nose for receiving a key to position the tumblers, a plurality of secondary tumblers surrounding the key nose, and means biasing the primary tumblers toward the secondary tumblers, but yieldable for movement of the primary tumblers in response to movement of the secondary tumblers by the said key.

5. A lock comprising a housing with a bolt slidable between extended and retracted positions, first and second key noses for receiving tumbler operating keys, a plurality of primary tumblers at least some of which are movable from positions normally blocking the retraction of the bolt to unblocking positions, a plurality of secondary tumblers positioned between the first key nose and the primary tumblers, the secondary tumblers being movable by the teeth of a key turned in the first key nose and the primary tumblers being movable upon movement of the secondary tumblers, the primary tumblers also being movable by rotation of a key within the second key nose, at least some of the normally blocking tumblers being movable to unblocking positions upon upon rotation of the proper sequence of the proper keys within the key noses, and a bolt blocking lever movable to unblocking position upon proper key action Within one of the key noses.

6. A lock having a retractable locking bolt, a plurality of tumblers normally blocking retraction of the bolt, first and second key noses, the first key nose being operable to establish one condition of the tumblers upon operation of the proper sequence of the proper keys therein, the second key nose being operable to establish a second condition of the tumblers upon operation of the proper key therein, the propriety of the key operable within the second key nose being dependent upon the aforesaid one position of the tumblers, and additional means normally blocking retraction of the bolt and movable to unblocking posi tion upon the establishment of the aforesaid one condition of the tumblers.

7. In a lock having a locking bolt that is retractable upon key operation of the lock, a plurality of tumblers, a lever normally blocking retraction of the bolt, means controlled by the positions of the tumblers for moving the lever to an unblocking position upon turning a proper key in the lock, and for returning the lever to the blocking position when the key is returned in the lock, and addi tional means controlled by the positions of the tumblers for blocking retraction of the bolt.

8. The lock of claim 7 wherein the lever is movable part of the way toward unblocking position upon the turning of a proper key prior to the turning of the first-mentioned key, the first inserted key being removable to allow insertion of the second key.

9. The lock of claim 8 wherein only the second inserted key is operable to return the lever to the blocking position.

10. The lock of claim 9 with means engageable by the last inserted key for returning the lever to blocking posi tion, and means for automatically positioning the engageable means for engagement by the last key inserted.

11. In a lock having a housing with a retractable bolt normally projecting from the housing, a plurality of tumblers, means supported by the bolt for alternately blocking and unblocking retraction of the bolt depending upon the positions of the tumblers, the tumblers being movable to positions for releasing the means to unblocking condition, means on the tumblers engageable by a first key introduced into the lock for establishing preliminary positions of the tumblers, means on the tumblers engageable by a second key introduced into the lock for moving the tumblers from the preliminary positions to the releasing positions, bolt blocking lever means normally positioned to block retraction of the bolt, and lever release means responsive to movement of the tumblers to their preliminary positions for releasing the bolt blocking lever means.

12. The lock of claim 11 with means for moving the bolt locking lever means to normal position upon removal of at least one of the keys.

13. The lock of claim 11 with means for preventing reading of the lock by sound detection means.

14. In a lock having a bolt and a plurality of tumblers, the positioning of the tumblers being a prerequisite to retraction of the bolt; first and second key noses for receiving keys to position the tumblers upon turning of at least one key, the key in the first key nose serving to establish preliminary positions of the tumblers, and the key in the second key nose serving to establish the position of the tumblers required for retraction of the bolt, and means for preventing reading of the key in the first key nose when there is no key in the first key nose.

15. The lock of claim 14 wherein the last mentioned means includes lost motion connections between the tumblers and the locking bolt.

16. The lock of claim 14 wherein the locking bolt has a lug on it normally obstructed by the edges of the tumblers from allowing retraction of the locking bolt and the tumblers have a plurality of slots alignable upon turning of the proper keys in the key noses for receiving the lug upon retraction of the bolt, the relationship between the slots and the lug allowing the tumblers to fall against the first key nose when bolt is retracted and there are no keys in the first key nose.

17. The lock of claim 14 wherein the last mentioned means includes means for delaying the re-extension of the the locking bolt during a substantial portion of the return rotation of a key in the second key nose.

18. In a lock: a plurality of floating tumblers in the lock, first and second key noses in the lock, each being adapted to receive keys, the tumblers extending adjacent both key noses; first operating means including a first key and operatable by said key in the first key nose for moving the first ends of the tumblers and second operating means including a key and operatable by the second key in the second key nose for moving the second ends of the tumblers, the tumblers having lug-receiving recesses at diiferent places adjacent the second end, that are aligned when both operating means are actuated by their keys; a bolt movable in the lock, means including a first lug moved by the bolt when the bolt is moved to lock-opening position, the lug being normally obstructed by the tumblers when the tumblers are not positioned to align their several recesses, but being free to move to lock-opening position when the recesses are aligned; additional movable means blocking opening movement of the bolt, and means to render the additional movable means ineffective to block the bolt, operated by the first 1operating means when the same is operated by the first 19. In the lock of claim 18: the additional movable means including a blocking member movable into and out or" bolt-blocking position; the means to render the movable means ineffective comprising other recesses at diflerent points on the tumblers that are aligned only when the tumblers are displaced by the first operating means, and means on the blocking member movable onto the said other recesses, whereby the blocking member is moved out of blocking position.

20. The lock of claim 19; with means operated by return movement of the first operating means to its start ing position to displace the blocking member out of said recesses to permit the tumblers to be displaced toward their starting positions.

21. The lock of claim 20, with movable abutting means between the blocking member and the bolt that is normally in position for blocking engagement between them when the bolt is in locking position and the first operating means is in initial position, but which is yieldable to permit the blocking member to move from operated to initial position without returning the bolt in locked position.

22. The lock of claim 18, wherein the second operating means includes a plurality of secondary tumblers having openings and surrounding the second key nose, to obstruct lock-picking instruments inserted through the second key nose from reaching the internal parts of the lock.

References Cited in the file of this patent UNITED STATES PATENTS 1,432,720 Mosely Oct. 17, 1922 1,439,042 Varnum et a1. Dec. 19, 1922 1,587,108 Eras June 1, 1926 1,665,015 Benham Apr. 3, 1928 2,524,696 Ellis Oct. 3, 1950 

4. IN A LOCK HAVING A HOUSING WITH A RETRACTABLE LOCKING BOLT, A PLURALITY OF PRIMARY TUMBLERS MOVABLE FROM POSITIONS NORMALLY BLOCKING RETRACTION OF THE BOLT TO UNBLOCKING POSITIONS, A SLOTED KEY NOSE FOR RECEIVING A KEY TO POSITION THE TUMBLERS, A PLURALITY OF SECONDARY TUMBLERS SURROUNDING THE KEY NOSE, AND MEANS BIASING THE PRIMARY TUMBLERS TOWARD THE SECONDARY TUMBLERS, BUT YIELDABLE FOR 